Originally posted by Eh
In GR, spacetime is a field (a classic field like Faraday's) defined entirely by the interactions of 3 sets of field lines. These field lines are all there is to the field, though their relations are constantly evolving.
I was afraid of that. It seems you want us to stay within GR. I'm trying to take another perspective, although I try to not get into contradictons with anything. You see, I don't want to stay within GR :)
As I said, you postulate both parts and relations. What are the field
lines made of? Why 3 sets of lines? Why not 12? Why not sphere radius and angles? Selection is really arbitrary, even if its the least necessary parts. How do relations 'attach' to field lines? See, you need to have some arbitrary definitions. Its just model.
I don't see how. Take away the geometry, and spacetime would disappear. At least in that sense, you cannot have time without it.
Ah, you have very strong preassumption that something must exist first to have time. That makes it hard for us to talk about it. I see that without time there is no existence. So there can't exist something first. You can take this as paradox, or take and say that time itself becomes that something.
Geometry is set of definitions. How you correlate reality with any sort of geometry is only through observation. And what you observe, is not necessarily exactly corresponding points of geometry. What makes geometry of observed is some set of equipotentials, vector equilibriums or consistently quantisisable distances. If you could be 'fooled' into perceiving some consistency, you'd admit its perfectly 3D geometry, even if its very far from true.
In that sense, 3D is illusion, but you are detached from truth because you are inside it and can never escape. As example, take rendered 3D 'reality' inside a computer. It has all necessary properties of 3D geometry, but, it is stored in RAM chips all over the place. True location of 3D points and their imaginary location 'from inside' are very different. For 'creature' inside such rendered world, 3D is real. But its only illusion.
In reality, it may be irrelevant what is true geometry, if what you observe is reduced to 3D consistently by some sort of relations. But it might become important when you look at the very structure of space itself. I think I'm saying that there may be arbitrary number of dimensions and we'd 'detect' only 3 not because others are curved, but because relations of existence don't let us detect anything in any other way. So, for eg, if your hand is located in other galaxy, but you can only observe it as here, you can't get around it. But, you still can have nonzero probabilities that its atoms happen to exist and interact in other galaxy.
For 3D illusion to exist, we need to have some means to quantify distances and relations between them. In this world, there are only that many means for that: measure of time. Everything goes on relative to that. Its time that makes distance to galaxy and your hand equal. Points that are at equal 'time steps' apart to reach them are observed as being at same distance, wherever they are.
I'm not sure exactly what you're trying to say. Hopefully the definition of the gravitational field should at least put us on the same page, and help show the point I was trying to make about there being no independent existence for time.
I don't want to argue GR. Its a working model. But I can't agree with you that this shows that there is no independant existence of time. GR doesn't really even bother about its independant existence. You postulated time as soon as you said 'interactions'. There is no room for interactions without concept of time. You can't interact.
Good example, let's go with it. You obviously cannot have a string without length, so that would certainly be the quanta of space. But what about time? If the string didn't do anything (namely vibrate) how could you say it has anything to do with time? So while it seems we could at least imagine a string without time, it is not possible to have such a string without geometric extent.
well, I can imagine aliens, that doesn't make them real. Let's better talk about how can you be aware of real string without any concept of time? How can you possibly 'measure' its extent?? And when I imagine string, I imagine dormant string in time, not just string outside time. When you try to detect a string, you have to interact with it. Without interacting, you can't possibly even know of its existence. Now, we have to ask, does interaction happen instantly? If not, then you again have introduced concept of fundamental time. Its uniform flow is the only means by which you could possibly measure (quantify) its extent. If you are the string, then yeah, no perception of time without 'vibrations'. But if you are observer, there is time without vibrations of string. Static timeless strings do not vibrate.
You're talking about the experience of conscious minds, right? I said, I can't defend the idea, and could only guess as to how a 4D existence would work with the existence of a mind.
No I'm not actually. I meant technical observation. What, do you mean that conscious mind is the only fool who has the illusion of time and existence?
Come to think of it, it was probably a bad example, since it has taken us off the original topic. The basic idea is still that we can well imagine a geometric object that doesn't change. To imagine change on the other hand, requires something existing in the first place, or so I would argue.
I think it was good example, and is quite well on subject, as this is often thought about and serious idea. I just tend to argue about it.
So you think that time is 'just change'. Your argue is essentially question 'what time is then if not change'. I don't know what time really is, but I think there is plenty of evidence that it is not just change. Perception of time is perception of change, agree. But fact that similar chain of changes can flow at differing rates shows that change alone is not real essence of time.
If I'd have to, I'd tie time to fundamental of existence, PoE, something that takes non-existence and creates existence from it, either by logic or acausal chance.
That would not be a correct definition of energy, since motion isn't involved in all forms of it.
well, I wanted to point that 'just change' is not correct definition of time, since change isn't involved in all forms of it.
No they wouldn't, because the events themselves take a certain amount of time. You don't need time between changes, because as soon asan event has ended, a new event has started. ]
Come on, you add fundamental time on every corner. Instant change + finite static time is equivalent to zero static time + finite change time. The only way to throw out time is to say that both, change instant and static state occur in zero time, which is essentially static 4D view.
I also don't see how the notion of frames of reference in relativity changes anything.
inertial frames. all laws are same in any inertial frame. If we still can have time difference in those frames, there is no explanation to timeflow as just matter of change.
Since we don't yet have a quantum theory of space or time, it really doesn't apply. .
We talked about wasteful usage of geometry. I think you can't build cube from infinite amount of zero-thickness plates.
Potential theories of spacetime such as string theory and loop quantum gravity do claim space and time are discrete, but you can't have time without the loops or string
I think you can. I think you can even go as far as to create space or loops from that alone. Its a matter of what you postulate. Postulate units of existence that have arbitrary finite time of dormant existence in undefined geometry before some interact and exchange their dormant existence duration. Only those that happen to be 'ready to go' in same instant can interact, forming all else as illusions, perceived time included.
Not more bizarre than strings.
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